Code Definition

P2003 — Secondary Air Injection System Circuit Malfunction

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Mercedes-Benz

About P2003

P2003 is a generic (obd-ii standard) powertrain diagnostic trouble code recorded for Mercedes-Benz vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P2003 is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P2003 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

This fault code indicates a malfunction in the secondary air injection (SAI) system circuit. The SAI system introduces fresh air into the exhaust stream to help reduce emissions during cold starts. The engine control module (ECM) monitors the operation of the SAI pump, valves, and associated circuits. If an electrical or functional issue is detected, this fault is set.

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